1. Field of the Invention
The present invention relates to a guide device for guiding a strip along a feed path.
2. Description of the Related Art
For blanking workpieces of given shape out of a metal strip, it has been customary to supply the metal strip continuously along a feed path to a blanking apparatus. Generally, a metal strip having a given length is wound as a coil, and unwound from the coil and fed along the feed path to the blanking apparatus.
The blanking apparatus blanks desired workpieces out of the supplied strip at successive positions thereon. Along the feed path, the strip is transversely centered with respect to the feed path such that the central axis of the strip is aligned with the central axis of the feed path for thereby allowing the strip to be positioned easily at the machining position in the blanking apparatus.
The strip may be centered by a pair of limiting members such as guide plates or abutment pins disposed one on each side of the feed path for engaging respective longitudinal edges of the strip to positionally limit the strip. The distance between the limiting members are equalized to the width of the strip.
There are available various strip coils of different dimensions, so that some strips to be supplied to the blanking apparatus have different widths. If the width of a strip unwound from a coil is smaller than the distance between the limiting members, then the strip tends to be positionally displaced transversely, and centered inaccurately. Conversely, if the width of a strip unwound from a coil is smaller than the distance between the limiting members, then the strip cannot pass between the limiting members, and cannot be fed to the blanking apparatus.
As shown in FIGS. 4(a) and 4(b) of the accompanying drawings, there are known strips each having thinner longitudinal marginal edges X, Y and a workpiece forming region Z extending between the thinner longitudinal marginal edges X, Y. For feeding such strips, the transverse center of the workpiece forming region Z across its width "d" is used as a reference for centering the strips.
One problem with the stripes shown in FIGS. 4(a) and 4(b) is that the width "b" of one of the thinner longitudinal marginal edges X and the width "c" of the other thinner longitudinal marginal edge Y may possibly differ from each other. If the widths "b", "c" are not the same as each other, then the transverse center of the strip across its full width "a" is not aligned with the transverse center of the workpiece forming region Z across its width "d". As a result, these strips cannot be centered highly accurately in alignment with the feed path by the limiting members.